Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Pseudomonas aeruginosa response to lung surfactant

ABSTRACT: The response of bacteria to the conditions at the site of infection is a key part of the transcriptional program that will determine the sucess of the infectious agent. To model the environment of the distal airway, we used bovine pulmonary surfactant (Survanta). P. aeruginosa transcript levels were measured in the presence or absence of Survanta in MOPS minimal medium to identify transcripts altered in response to surfactant. The most highly induced transcript in Survanta was PA5325, renamed sphA based on our findings that the gene was specifically induced by sphingosine derived from the sphingomyelin present in pulmonary surfactant. A divergently transcribed transcription factor, PA5324, was demonstrated to be critical for the sphingosine dependent induction of sphA and was therefore renamed SphR. Microarrays of the sphR mutant cells were compared to wild type to determine the likely SphR regulon. Wild type and sphR mutant cells were pre-grown in MOPS minimal media and then split and resuspended in MOPS pyruvate or MOPS pyruvate + surfactant

ORGANISM(S): Pseudomonas aeruginosa

SUBMITTER: Matthew Wargo

PROVIDER: E-GEOD-48982 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Malic enzymes decarboxylate the tricarboxylic acid (TCA) cycle intermediate malate to the glycolytic end-product pyruvate and are well positioned to regulate metabolic flux in central carbon metabolism. The bacterium Sinorhizobium meliloti has a NAD(P)-malic enzyme (DME) and a NADP-malic enzyme (TME) and DME is required for symbiotic N2-fixation. To help understand the role of these enzymes, we examined growth, metabolic and transcriptional consequences resulting from the deletion of these enzymes. Few effects were observed upon growth with glucose, whereas growth with the gluconeogenic substrate, succinate, resulted in transcriptional and metabolic effects particularly in the dme mutant strains. When grown with succinate, DME mutant cells accumulated hexose sugar phosphates and trehalose, while TME mutants accumulated putrescine. Succinate-grown DME mutant cells also showed increased transcription of genes for gluconeogenesis and for pathways such as amino acid and fatty acid synthesis that divert metabolites away from the TCA cycle. These data suggested that, DME is required to regulate the levels of TCA cycle intermediates and that the activity of TME is insufficient to prevent the accumulation of TCA cycle intermediates in cells utilizing succinate as carbon source. Consistent with this, in short-1-3 hour incubations with succinate, dme mutant cells excreted large amounts of malate whereas little malate was excreted from tme or wild-type cells. These results support the suggestion that DME is required for N2-fixation in alfalfa because it is required for synthesis of pyruvate and acetyl-CoA and the rapid metabolism of C4-dicarboxylates supplied by the plant. RNA expression was measured for S. meliloti in exponential phase grown in MOPS (morpholinpropanesulfonic acid) buffered minimal media under 2 growth conditions: 1) 15 mM succinate, 2) 15 mM glucose; using wild type cells as well as dme and tme mutant strains (6 experiments, 2 replicates: total 12 samples)

Project description:Transcription profiling of wild type E. coli MG1655, intestine-adapted E. coli MG1655star, and E. coli MG1655 flhD mutant grown on glucose, mannose, and mucus. We previously isolated a spontaneous mutant of E. coli K-12, strain MG1655, following passage through the streptomycin-treated mouse intestine, which has colonization traits superior to the wild-type parent strain (Leatham, et. al., 2005, Infect Immun 73:8039-49) The intestine-adapted strain (E. coli MG1655star) grew faster on several different carbon sources compared to the wild-type and was non-motile due to deletion of the flhD gene. To further characterize E. coli MG1655star, we used several high-throughput genomic approaches. Whole-genome pyrosequencing did not reveal any changes on its genome, aside from the deletion at the flhDC locus, that could explain the colonization advantage of E. coli MG1655star. Microarray analysis revealed modest, yet significant induction of catabolic gene systems across the genome in both E. coli MG1655star and the isogenic flhD mutant. Catabolome analysis with Biolog GN2 Microplates revealed an enhanced ability of both E. coli MG1655star and the isogenic flhD mutant to oxidize a wide variety of carbon sources. The results show that intestine-adapted E. coli MG1655star is more fit than the wild-type for intestinal colonization because loss of FlhD results in elevated expression of genes involved in carbon and energy metabolism, leading to more efficient carbon source utilization, which results in a higher population size in the intestine. Hence mutations that enhance metabolic efficiency confer a colonization advantage. Three strains were profiled: E. coli MG1655 wildtype, E. coli flhD, and an intestine adapted strain, MG1655star, derived from the wildtype and isolated from feces after 15 days in the streptomycin treated mouse intestine, which proved to be a better colonizer than the wildtype, were grown on MOPS minimal medium containing 0.2% glucose or mannose, or mucus (10 mg/ml) and RNA was extracted from logarithmic phase cultures, and also from mucus grown cells in late log phase.

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Pseudomonas aeruginosa response to lung surfactant

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